Metabolism is required for chemotaxis to sugars in Rhodobacter sphaeroides.
Chemotaxis towards carbohydrates is mediated, in enteric bacteria, either by the transport-independent, methylation-dependent chemotaxis pathway or by transport and phosphorylation via the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS). This study shows that Rhodobacter sphaeroides is chemotactic to a range of carbohydrates but the response involves neither the classical methyl-accepting chemotaxis protein (MCP) pathway nor the PTS transport pathway. The chemoattractant fructose was transported by a fructose-specific PTS system, but transport through this system did not appear to cause a chemotactic signal. Chemotaxis to sugars was inducible and occurred with the induction of carbohydrate transport systems and with substrate incorporation. A mutation of the glucose-6-phosphate dehydrogenase gene (zwf) inhibited chemotaxis towards substrates metabolized by this pathway although transport was unaffected. Chemotaxis to other, unrelated, chemoattractants (e.g. succinate) was unaffected. These data, in conjunction with the fact that mannitol and fructose (which utilize different transport pathways) compete in chemotaxis assays, suggest that in R. sphaeroides the chemotactic signal is likely to be generated by metabolic intermediates or the activities of the electron-transport chain and not by a cell-surface receptor or the rate or mode of substrate transport.
Jeziore-Sassoon
Yehudit
Y
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Hamblin
Paul A
PA
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Bootle-Wilbraham
Carolyn A
CA
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Poole
Philip S
PS
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Armitage
Judith P
JP
Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
D001692:Biological Transport; D002465:Cell Movement; D002633:Chemotaxis / Q000502:physiology*; D005631:Fructokinases / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D008354:Mannitol Dehydrogenases / Q000378:metabolism; D008745:Methylation; D009005:Monosaccharides / Q000378:metabolism*; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism; D010732:Phosphofructokinase-1 / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
D009005:Monosaccharides; D008354:Mannitol Dehydrogenases; D005954:Glucosephosphate Dehydrogenase; D005631:Fructokinases; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D010732:Phosphofructokinase-1; C046173:fructokinase; C068652:1-phosphofructokinase